On behalf of the Program Committee, we are pleased to announce that The 9th International Symposium on Ultrafast Phenomena and Terahertz Waves (ISUPTW 2018) will be held in Changsha, China from April 23 to 26, 2018. ISUPTW 2018 is organized by National University of Denfense Technology (NUDT) and the Optical Society of America (OSA). More information will be released in the website. ISUPTW, an international symposium, is devoted to strengthening the collaboration among worldwide researchers and promoting the development in Ultrafast and Terahertz science and technology. The biennial symposium, initiated in 2002, has been held in Beijing, Shanghai, Nanjing, Tianjin, Xi'an, and Wuhan. It brings together scientists, technologists, and students from more than 10 countries and typically hosts 150-300 participants. This symposium provides an excellent opportunity to share and exchange ideas. We look forward to welcoming our friends and colleagues from all around the world. The paper submission system is open now. We warmly invite you and your colleagues as well as students to submit the latest work. The contributed papers will be archived on EI Compendex by OSA. We believe you will not only enjoy the exchange and discussions on ultrafast phenomena and terahertz wave, but will also have a memorable experience in Changsha, China.